Set a color to transparent

[cyse]

Hello guys,

I can't find how I tell löve X color should be transparent!

I want brown (106, 76, 48): to be displayed as transparent.

I added in love.load()

Code: Select all

	love.graphics.setBackgroundColor(106, 76, 48)

But it doesn't work:


I would like my little miner and the rocks without brown, just on a the grass.

Should I use:
- PixelEffect ? viewtopic.php?f=4&t=10112&hilit=transparent -> I don't understand how I could do what I want
- Convert my PNG's to 8 bit colors and replace brown (6A4C30) by alpha: How could I do this in a batch? I have too many files to do this one by one

Any idea?

thx

[Jasoco]

Yes. You need to use a PNG with transparency. Löve doesn't have the "use a specific color as a transparent mask" feature that I know of. We just use PNG's with transparent backgrounds. Convert all your images now. And get used to using transparency in the future. I haven't used a colored mask since my DOOM editing days. Soooo much magenta!!!

[kikito]

I'd also like to point out that PNGs allows for partial transparency on the alpha channel, which can make your borders look better (unless you are going for a "pixelated" effect, of course)

[Kadoba]

You can load your image as image data first and then use ImageData:mapPixel() to alter a specific color to have zero alpha.

Code: Select all

local function loadTransparent(imagePath, transR, transG, transB)

   local imageData = love.graphics.newImageData( imagePath )

    local function mapFunction(r,g,b,a)
        if r == transR and g == transG and b == trangB then a = 0 end
        return r,g,b,a
    end

    imageData:mapPixel( mapFunction )

    return love.graphics.newImage( ImageData )

end

[Ref]

Can remove backfround using pixel effects (much faster than mapPixel) but as pointed out before the results will most likely be unsatisfactory because of how the image was originally created (edge shading).
As always, best to start with quality rather than trying to patch.

[Zeliarden]

here is a fixed ver of Kadoba code

Code: Select all

function loadTransparent(imagePath, transR, transG, transB)
	imageData = love.image.newImageData( imagePath )
	function mapFunction(x, y, r, g, b, a)
		if r == transR and g == transG and b == transB then a = 0 end
		return r,g,b,a
	end
	imageData:mapPixel( mapFunction )
	return love.graphics.newImage( imageData )
end

[josefnpat]

If you use gimp, you can also use the "Select by Color" tool to get all of the brown in a spritesheet.

7ShGV.png (128.14 KiB) Viewed 980 times

[cyse]

thank you all for the answers! I'll try each solution until I'm happy with the result

Removing the brown is effectively unsatisfactory but josefnpat's version seems good though: I'll try it with gimp.

thanks all - I'll post the result (in a few months - I won't get that much free time before that).